Light bulb



FIG. 1 is a perspective view of a light bulb embodying my new design;

FIG. 2 is an elevational front view thereof, the opposite side being identical;

FIG. 3 is an elevational side view thereof, the opposite side being identical;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a light bulb, as shown and described. 